Strapping and methods of making the same

ABSTRACT

An article includes about 85.5 wt % to about 99.85 wt % of a polyester, and about 0.15 wt % to about 4.5 wt % of a polyolefin co-polymer, where the polyolefin co-polymer is polymerized from monomers including about 10 wt % to about 90 wt % of propylene or one or more (meth)acrylates, and about 10 wt % to about 90 wt % of an olefin other than propylene or a (meth)acrylate, where the article is a strapping article.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority from U.S. Provisional PatentApplication No. 61/549,659, filed Oct. 20, 2011, which is incorporatedhereby by reference in its entirety.

FIELD

Provided herein are strapping compositions made from polyester and apolyolefin co-polymer. More specifically, polyester-based strappings areprovided that exhibit commercially useful combinations of physicalproperties such as seal strength, tension retention, resistance tosplitting, and maintenance of polyester's traditional color andtranslucence. Also provided are methods of making such strappingcompositions.

BACKGROUND

Polyester-based strapping is commonly used in the packaging industry tocombine, hold, reinforce, or fasten items. Commercial strapping requiresa combination of physical properties that can be difficult toincorporate into a single composition in a cost-effective manner. Forexample, the strapping must have sufficient tensile strength along itslongitudinal axis without being susceptible to significant lengthwisesplitting. The strapping should maintain an initial tension over aperiod of time and concede minimal stress relaxation. As used hereinstress relaxation is the loss of initial tension. Critically, thestrapping must also exhibit sufficient tension retention which keeps thestrapping tight around the load, even if the load settles, shifts, orshrinks in size. After being wrapped around an object, the strappingends are drawn tightly together and fused to form a seal. Typically, thefused seal represents the weakest point of the strapping and, thus, thepoint most susceptible to failure. Under heavy loads the seal is usuallymore apt to separate when the strapping is snapped across its width uponbeing released from the sealing equipment. Thus, great seal strength atthe fused ends and a resistance to splitting or breaking after sealingare critical properties of commercial strapping.

Pure polyester strapping is strong and inexpensive, but fails to providea full range of above-indicated properties. Relatively costly polyolefinco-polymer additives have been added to polyester-based strapping toimprove some of these properties, such as resistance to splitting, butthese additives may not sufficiently improve other properties such asseal strength and tension retention. Certain additives may also discolorthe strapping, (e.g., strapping made from polyethylene terephthalate(PET)), such as by turning it opaque or milky, which can interfere withthe operation of the strapping equipment (e.g., optical sensors), andcan also be less visually appealing to customers. Consequently, thereremains a significant need to identify polyolefin co-polymer additivesand new polyester strapping compositions with sufficient seal strength,tension retention, resistance to splitting, and maintenance of PET'straditional color and translucence.

SUMMARY

Applicant has discovered strapping compositions having commerciallyuseful combinations of physical properties such as seal strength,tension retention, resistance to splitting, and maintenance of PET'straditional color and translucence, prepared from a mixture of polymersthat includes a polyester and a polyolefin co-polymer.

In one aspect, a strapping composition is provided that includes about85.5 wt % to about 99.85 wt % of a polyester and about 0.15 wt % toabout 4.5 wt % of a polyolefin co-polymer. The polyolefin co-polymer ispolymerized from monomers including about 10 wt % to about 90 wt % ofpropylene or one or more (meth)acrylates and about 10 wt % to about 90wt % of an olefin other than propylene or a (meth)acrylate. In certainembodiments, the strapping composition further includes about 0.01 wt %to about 10 wt % of a polycarbonate and/or a polyamide such as nylon.

Some of the polyester-based strapping compositions described hereininclude polyolefin co-polymers that derive, in part, from propylene. Insome embodiments, the polyolefin co-polymer is polymerized from monomersincluding about 26 wt % to about 90 wt % propylene and about 10 wt % toabout 74 wt % of the olefin other than propylene or a (meth)acrylate,such as, for example, ethylene. In some embodiments, the polyolefinco-polymer is polymerized from monomers consisting essentially of about26 wt % to about 39 wt % propylene and about 61 wt % to about 74 wt % ofthe olefin other than propylene or a (meth)acrylate. The one or moreolefins may optionally include a diene. In some embodiments, thepolyolefin co-polymer is polymerized from monomers consistingessentially of about 26 wt % to about 39 wt % propylene, about 61 wt %to about 74 wt % of the olefin other than propylene or a (meth)acrylate,and about 0.1 wt % to about 10 wt % of a diene. In certain embodiments,the strapping composition includes about 1.2 wt % to about 2.5 wt % ofthe polyolefin co-polymer.

Other polyester-based strapping compositions described herein includepolyolefin co-polymers that derive, in part, from one or more(meth)acrylates. In some embodiments, the polyolefin co-polymer ispolymerized from monomers including about 10 wt % to about 50 wt % ofone or more (meth)acrylates, and about 50 wt % to about 90 wt % of theolefin other than propylene or a (meth)acrylate, such as, for example,ethylene. In certain embodiments, the strapping composition includesabout 1.2 wt % to about 2.5 wt % of the polyolefin co-polymer.

The polyester-based strapping compositions described herein may includepolyolefin co-polymers that include a diene such as ethylidenenorbornene(ENB). In certain embodiments, the polyolefin co-polymer is polymerizedfrom monomers including about 29 wt % propylene, about 70.5 wt % of oneor more olefins other than propylene or a (meth)acrylate, and about 0.5wt % of the diene. In some embodiments, the olefin other than propyleneor a (meth)acrylate includes ethylene. In certain embodiments, thepolyester includes polyethylene terephthalate, the olefin other thanpropylene or a (meth)acrylate includes ethylene, and the diene includesethylidenenorbornene (ENB).

As noted, the strapping compositions described herein arepolyester-based. In certain embodiments, the polyester includespolyethylene terephthalate or copolymers of polyethylene terephthalate.In certain embodiments, the polyester includes recycled or reprocessedpolyester.

In some aspects, the strapping is contemplated for heavy-dutyapplications having a width of at least about ⅝ inches (15 mm). Forexample, heavy-duty strapping with dimensions ⅝″×0.35″ generallyexhibits a break strength of at least about 1,300 lbs (591 kgs) of load,whereas heavy-duty strapping with dimensions ⅝″×0.40″ generally exhibitsa break strength of about 1,500 lbs (682 kgs) of load. Heavy-dutypolyester strapping is especially prone to splitting, at least in partdue to its dimensions (i.e., extra thickness) and the higher tensions itis exposed to during fastening and use. Further, in some applications,heavy-duty strapping must be fitted with “bumpers” that prevent theedges of the tightly wrapped strapping from digging into and damagingfastened goods such as lumber. It is thus contemplated that heavy-dutystrapping with a width of at least about ⅝ inches (15 mm) and,optionally, a thickness of about 0.018 inches (0.46 mm) to about 0.035inches (0.70 mm) or, alternatively, exhibiting a break strength of atleast about 1,300 lbs (591 kgs) of load, can be prepared from thecompositions described herein to have a reduced incidence of splitting.Reduced splitting can allow the strapping to be produced relatively thinand wide. In certain embodiments, heavy-duty strapping is greater than 1inch (25.4 mm) wide or, in other embodiments, greater than 1¼ inches(31.8 mm) wide which, in turn, can reduce the need to use protectivebumpers in heavy-duty applications.

In another aspect, provided herein is a method of manufacturing anarticle, where the article is a strapping composition. The method ofmanufacturing the strapping composition includes the steps of forming amixture, heating the mixture, and extruding the heated mixture to formthe strapping, where the mixture includes about 85.5 wt % to about 99.85wt % of a polyester; and about 0.15 wt % to about 4.5 wt % of apolyolefin co-polymer, where the polyolefin co-polymer is polymerizedfrom monomers including about 10 wt % to about 90 wt % of propylene orone or more (meth)acrylates, and about 10 wt % to about 90 wt % of anolefin other than propylene or a (meth)acrylate.

In certain embodiments of the method, the mixture that is formed furtherincludes about 0.01 wt % to about 10 wt % of a polycarbonate and/orpolyamide such as nylon. In some embodiments, the one or more olefinsother than propylene include a diene, such as ethylidenenorbornene(ENB).

In certain embodiments of the method, the polyester, such as PET, thatis included in the mixture has an intrinsic viscosity of about 0.70 dl/gto about 0.84 dl/g. In other embodiments, the polyester, such as PET,has an intrinsic viscosity of about 0.78 dl/g to about 0.82 dl/g. In yetother embodiments, the polyester, such as PET, has an intrinsicviscosity of about 0.76 dl/g to about 0.80 dl/g, or about 0.74 dl/g toabout 0.78 dl/g. In certain embodiments, the PET includes recycled PET.In other embodiments, the PET includes reprocessed PET.

In certain embodiments of the method, the mixture is extruded from asingle-screw extruder. In other embodiments, the method of manufacturinga strapping composition further includes the step of stretching thestrapping about 3 to about 7 times an initial, unstretched length of thestrapping.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 graphically illustrates the split testing results of Table 5 bydisplaying the percentage of straps that were split relative to thetotal number of split tests that were run on each strap. Thecompositions of straps A, B, C, and D1-D5 are described in Table 5.

DETAILED DESCRIPTION

The illustrative embodiments described in the detailed description,drawings, and claims are not meant to be limiting. Other embodiments maybe utilized, and other changes may be made, without departing from thespirit or scope of the subject matter presented here.

The technology is described herein using several definitions, as setforth throughout the specification.

As used herein, “about” will be understood by persons of ordinary skillin the art and will vary to some extent depending upon the context inwhich it is used. If there are uses of the term which are not clear topersons of ordinary skill in the art, given the context in which it isused, “about” will mean up to plus or minus 10% of the particular term.

As used herein, the term (meth)acrylic monomer refers to acrylic ormethacrylic acid, esters of acrylic or methacrylic acid, and salts,amides, and other suitable derivatives of acrylic or methacrylic acid,and mixtures thereof. Examples of suitable acrylic monomers include,without limitation, the following methacrylate esters: methylmethacrylate, ethyl methacrylate, n-propyl methacrylate, n-butylmethacrylate (BMA), isopropyl methacrylate, isobutyl methacrylate,n-amyl methacrylate, n-hexyl methacrylate, isoamyl methacrylate,2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate,N,N-dimethylaminoethyl methacrylate, N,N-diethylaminoethyl methacrylate,t-butylaminoethyl methacrylate, 2-sulfoethyl methacrylate,trifluoroethyl methacrylate, glycidyl methacrylate (GMA), benzylmethacrylate, allyl methacrylate, 2-n-butoxyethyl methacrylate,2-chloroethyl methacrylate, sec-butyl-methacrylate, tert-butylmethacrylate, 2-ethylbutyl methacrylate, cinnamyl methacrylate, crotylmethacrylate, cyclohexyl methacrylate, cyclopentyl methacrylate,2-ethoxyethyl methacrylate, furfuryl methacrylate, hexafluoroisopropylmethacrylate, methallyl methacrylate, 3-methoxybutyl methacrylate,2-methoxybutyl methacrylate, 2-nitro-2-methylpropyl methacrylate,n-octylmethacrylate, 2-ethylhexyl methacrylate, 2-phenoxyethylmethacrylate, 2-phenylethyl methacrylate, phenyl methacrylate, propargylmethacrylate, tetrahydrofurfuryl methacrylate and tetrahydropyranylmethacrylate. Example of suitable acrylate esters include, withoutlimitation, methyl acrylate, ethyl acrylate, n-propyl acrylate,isopropyl acrylate, n-butyl acrylate (BA), n-decyl acrylate, isobutylacrylate, n-amyl acrylate, n-hexyl acrylate, isoamyl acrylate,2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate,N,N-dimethylaminoethyl acrylate, N,N-diethylaminoethyl acrylate,t-butylaminoethyl acrylate, 2-sulfoethyl acrylate, trifluoroethylacrylate, glycidyl acrylate, benzyl acrylate, allyl acrylate,2-n-butoxyethyl acrylate, 2-chloroethyl acrylate, sec-butyl-acrylate,tert-butyl acrylate, 2-ethylbutyl acrylate, cinnamyl acrylate, crotylacrylate, cyclohexyl acrylate, cyclopentyl acrylate, 2-ethoxyethylacrylate, furfuryl acrylate, hexafluoroisopropyl acrylate, methallylacrylate, 3-methoxybutyl acrylate, 2-methoxybutyl acrylate,2-nitro-2-methylpropyl acrylate, n-octylacrylate, 2-ethylhexyl acrylate,2-phenoxyethyl acrylate, 2-phenylethyl acrylate, phenyl acrylate,propargyl acrylate, tetrahydrofurfuryl acrylate and tetrahydropyranylacrylate.

As used herein, the term “co-polymer” refers to polymers prepared frommore than one distinct monomer. As used herein, a co-polymer may beprepared from, for example, two, three, four, five, etc., distinctmonomers.

In a first aspect, strapping compositions are provided that exhibituseful combinations of physical properties such as seal strength,tension retention, resistance to splitting, and maintenance of thepolyester strapping's traditional color and translucence. A combinationof physical properties is required of commercially useful strappings.First, the strapping should be strong. Specifically, it should havesufficient tensile strength along its longitudinal axis to withstandheavy loads without breaking. Further, the strapping should not be toobrittle. Brittle strapping has a tendency to split along its length. Thestrapping should exhibit sufficient seal strength as the strapping istightly wrapped around an object and fused together at the ends to forma seal. This seal may have to withstand heavy loads without being pulledapart. Also, the strapping should exhibit flexibility, or tensionretention, to remain tight around the wrapped load, even if the loadsettles, shifts, or shrinks in size. Finally, for some customers or forcertain equipment, the strapping color can be important, particularlythe strapping's translucence to light.

Combinations of the above-described physical properties can be difficultto incorporate into a single strapping composition in a cost-effectivemanner. Relatively costly polyolefin co-polymer additives have beenadded to polyester-based strapping to improve some, but not all, ofthese properties. Provided are polyolefin co-polymer additives whichhave been identified that, when added to polyester, provide strappingcompositions with sufficient combinations of physical properties such asseal strength, tension retention, reduced splitting and/or maintenanceof the strapping's translucence to light.

In one aspect, a strapping composition is provided that includes about85.5 wt % to about 99.85 wt % of a polyester and about 0.15 wt % toabout 4.5 wt % of a polyolefin co-polymer. The polyolefin co-polymer maybe polymerized from monomers including about 10 wt % to about 90 wt % ofpropylene or one or more (meth)acrylates and about 10 wt % to about 90wt % of an olefin other than propylene or a (meth)acrylate.

Some of the polyester-based strapping compositions described hereininclude polyolefin co-polymers that derive, in part, from propylene.Thus, in some embodiments, the polyolefin co-polymer is polymerized frommonomers including about 26 wt % to about 90 wt % propylene and about 10wt % to about 74 wt % of the olefin other than propylene or a(meth)acrylate. In some embodiments, the polyolefin co-polymer ispolymerized from monomers consisting essentially of about 26 wt % toabout 39 wt % propylene and about 61 wt % to about 74 wt % of the olefinother than propylene or a (meth)acrylate.

Some of the polyester-based strapping compositions described hereininclude polyolefin co-polymers that additionally derive, in part, from adiene. For example, in some embodiments, the polyolefin co-polymerincludes one or more olefins other than propylene or a (meth)acrylate,such as ethylene and a diene. In some embodiments, the polyolefinco-polymer is polymerized from monomers consisting essentially of about26 wt % to about 39 wt % propylene; about 61 wt % to about 74 wt % ofthe olefin other than propylene or a (meth)acrylate and about 0.1 wt %to about 10 wt % of a diene. In any of the embodiments described herein,the diene is ethylidene norbornene (ENB), norbornadiene,oxanorbornadiene, dicyclopentadiene, an (alpha, omega)-diene, orcombinations thereof.

In certain embodiments, the strapping includes a polyolefin co-polymer,where the polyolefin co-polymer is polymerized from monomers includingpropylene, ethylene, and ENB. In some embodiments, the strappingincludes a polyolefin co-polymer, where the polyolefin co-polymer ispolymerized from monomers including about 27 wt % to about 31 wt %propylene, about 68 wt % to about 73 wt % of the olefin other thanpropylene or a (meth)acrylate, and about 0.1 wt % to about 5 wt % of thediene. In some embodiments, the polyolefin co-polymer is polymerizedfrom monomers including about 29 wt % propylene, about 70.5 wt % of theolefin other than propylene or a (meth)acrylate, and about 0.5 wt % ofthe diene.

In certain embodiments, the strapping is prepared from a polyolefinco-polymer that is polymerized from propylene, ethylene, and ENB as setforth below in Table 1.

TABLE 1 Exemplary polyolefin co-polymers Propylene Ethylene ENB Batch wt% wt % wt % a 57.3 42 0.7 b 43.2 55 1.8 c 29.4 70 0.6 d 29 70.5 0.5 e29.5 70 0.5 f 30.8 67 2.2 h 45.1 50 4.9 i 40.1 55 4.9 j 25.1 70 4.9 k28.1 67 4.9 n 27.1 68 4.9 p 42.5 50 7.5

In other embodiments, the strapping includes a polyolefin co-polymer,where the polyolefin co-polymer is polymerized from monomers includingpropylene, ethylene, or styrene, or mixtures thereof, and one or moredienes. In certain embodiments, the diene is ethylidene norbornene(ENB). In other embodiments, the polyolefin co-polymer is polymerizedfrom mixtures of propylene-ethylene-diene or styrene-butadiene.

Where the strapping composition include a diene, the amount of dieneadded to the polyolefin co-polymer of the polyester-based strappingcompositions can and will vary. In certain embodiments, the polyolefinco-polymer is polymerized from monomers including about 0.2 wt % toabout 0.5 wt % of one or more dienes. In certain embodiments, thepolyolefin co-polymer is polymerized from monomers including about 0.5wt % to about 1.0 wt % of one or more dienes. In certain embodiments,the polyolefin co-polymer is polymerized from monomers including about1.0 wt % to about 1.2 wt % of one or more dienes. In certainembodiments, the polyolefin co-polymer is polymerized from monomersincluding about 1.2 wt % to about 1.4 wt % of one or more dienes. Incertain embodiments, the polyolefin co-polymer is polymerized frommonomers including about 1.4 wt % to about 1.6 wt % of one or moredienes. In certain embodiments, the polyolefin co-polymer is polymerizedfrom monomers including about 1.6 wt % to about 1.8 wt % of one or moredienes. In certain embodiments, the polyolefin co-polymer is polymerizedfrom monomers including about 1.8 wt % to about 2.0 wt % of one or moredienes. In certain embodiments, the polyolefin co-polymer is polymerizedfrom monomers including about 2.0 wt % to about 3.0 wt % of one or moredienes. In certain embodiments, the polyolefin co-polymer is polymerizedfrom monomers including about 3.0 wt % to about 4.0 wt % of one or moredienes. In certain embodiments, the polyolefin co-polymer is polymerizedfrom monomers including about 4.0 wt % to about 8.0 wt % of one or moredienes. In certain embodiments, the polyolefin co-polymer is polymerizedfrom monomers including about 8.0 wt % to about 15.0 wt % of one or moredienes.

Some of the polyester-based strapping compositions described hereininclude propylene-based polyolefin co-polymers that derive, in part,from one or more (meth)acrylates. In some embodiments, the polyolefinco-polymer is polymerized from monomers including: about 10 wt % toabout 50 wt % of one or more (meth)acrylates; and about 50 wt % to about90 wt % of the olefin other than propylene or a (meth)acrylate. In someembodiments, the polyolefin co-polymer is polymerized from monomersconsisting essentially of: about 10 wt % to about 50 wt % of one or more(meth)acrylates; and about 50 wt % to about 90 wt % of the olefin otherthan propylene or a (meth)acrylate.

In some embodiments, the polyolefin co-polymer is polymerized frommonomers including about 10 wt % to about 20 wt % one or more(meth)acrylates and about 80 wt % to about 90 wt % ethylene. In someembodiments, the polyolefin co-polymer is polymerized from monomersincluding about 21 wt % to about 30 wt % one or more (meth)acrylates andabout 70 wt % to about 79 wt % ethylene. In some embodiments, thepolyolefin co-polymer is polymerized from monomers including about 31 wt% to about 40 wt % one or more (meth)acrylates and about 60 wt % toabout 69 wt % ethylene. In some embodiments, the polyolefin co-polymeris polymerized from monomers including about 15 wt % to about 40 wt %one or more (meth)acrylates and about 60 wt % to about 85 wt % ethylene.

In some embodiments, the strapping composition includes a polyolefinco-polymer, the polyolefin co-polymer includes one or more(meth)acrylates, and the (meth)acrylates include butyl acrylate, methylacrylate, glycidyl (meth)acrylate, methyl (meth)acrylate, or acombination of any two or more thereof.

In certain embodiments, the strapping composition includes a polyolefinco-polymer, and the polyolefin co-polymer includes anacrylate-comprising Lotryl® co-polymer as shown in Table 2. Lotryl®co-polymers are supplied by Arkema Inc., of Colombes, France. In certainembodiments, the polyolefm co-polymer includes Lotryl® 17 BA 04(deriving about 16% to about 19% butyl acrylate and about 81% to about84% ethylene), Lotryl® 17 BA 07 (deriving about 16% to about 19% butylacrylate and about 81% to about 84% ethylene), Lotryl® 28 BA 175(deriving about 26% to about 30% butyl acrylate and about 70% to about74% ethylene), Lotryl® 30 BA 02 (deriving about 27% to about 32% butylacrylate and about 68% to about 73% ethylene), Lotryl® 35 BA 40(deriving about 32% to about 37% butyl acrylate and about 63% to about78% ethylene) or Lotryl® 35 BA 320 (deriving about 32% to about 37%butyl acrylate and about 63% to about 78% ethylene). In someembodiments, the polyolefin co-polymer includes Lotryl® 30 BA 02. Inother embodiments, the polyolefin co-polymer includes Lotryl® 35 BA 40.

In some embodiments, the polyolefin co-polymer includes one or more(meth)acrylates such as butyl acrylate. In some embodiments, the one ormore (meth)acrylates consists essentially of butyl acrylate. In someembodiments, the polyolefin co-polymer is Lotryl® 17 BA 04, Lotryl® 17BA 07, Lotryl® 28 BA 175, Lotryl® 30 BA 02, Lotryl® 35 BA 40, or Lotryl®35 BA 320. In some embodiments, the polyolefin co-polymer is Lotryl® 30BA 02 or Lotryl® 35 BA 40.

In other embodiments, the polyolefin co-polymer includes Lotryl® 18 MA02 (deriving about 17% to about 20% methyl acrylate and about 80% toabout 83% ethylene), Lotryl® 20 MA 08 (deriving about 19% to about 22%methyl acrylate and about 78% to about 81% ethylene), Lotryl® 24 MA 005(deriving about 23% to about 26% methyl acrylate and about 74% to about77% ethylene), Lotryl® 24 MA 02 (deriving about 23% to about 26% methylacrylate and about 74% to about 77% ethylene) or Lotryl® 29 MA 03(deriving about 27% to about 31% methyl acrylate and about 69% to about73% ethylene).

In some embodiments, the polyolefin co-polymer includes one or more(meth)acrylates such as methyl acrylate. In some embodiments, the one ormore (meth)acrylates consists essentially of methyl acrylate. In someembodiments, the polyolefin co-polymer is Lotryl® 18 MA 02, Lotryl® 20MA 08, Lotryl® 24 MA 005, Lotryl® 24 MA 02, or Lotryl® 29 MA 03.

TABLE 2 Exemplary Lotryl ® polyolefin/acrylate co-polymers Tensile MeltMelting strength Elongation Lotryl ® Acrylate Index Point at break atbreak Grade (%) (g/10 mn) (C. °) (MPa) (%) Butyl 17 BA 04 16-19 3.5-4.593 15 700 Acrylate 17 BA 07 16-19 6.5-8.0 89 14 700 (BA) Co- 28 BA 17526-30 150-200 80 3 750 Polymers 30 BA 02 27-32 1.5-2.5 78 6 850 35 BA 4032-37 35-45 66 2 300 35 BA 320 32-37 260-350 65 1.5 200 Methyl 18 MA 0217-20 2-3 83 13 700 Acrylate 20 MA 08 19-22 7-9 80 9 800 (BA) Co- 24 MA005 23-26 0.4-0.6 72 17 750 Polymers 24 MA 02 23-26 1-3 68 9 750 29 MA03 27-31 2.0-3.5 61 6 900

In certain embodiments, the polyolefin co-polymer includes anacrylate-comprising Lotader® co-polymer supplied by Arkema Inc., ofColombes, France. Lotryl® co-polymers include Lotader® MAH (derived fromethylene, methyl acrylate, ethyl acrylate, butyl acrylate, and maleicanhydride) Maleic Anhydride) and Lotader® GMA (derived from ethylene,methyl acrylate, and glycidyl methacrylate). In certain embodiments, thepolyolefin co-polymer includes a Lotader® MAH terpolymer as shown inTable 3.

TABLE 3 Exemplary Lotader ® MAH terpolymers Tensile Acrylic Melt MaleicMelting Strength Elongation Lotader ® Acrylic Ester Index AnhydridePoint at break at Break Grade Ester (%) (g/10 mn) (%) (° C.) (MPa) (%)3210 BA 6 5 3.1 107 12 600 4210 BA 6.5 9 3.6 105 10 650 6200 EA 6.5 402.8 102 6 600 8200 EA 6.5 200 2.8 100 6 400 LX 4110 EA 5 5 3 105 11 650TX 8030 EA 13 3 2.8 95 12 700 HX 8290 EA 17 70 2.8 85 6 500 3410 BA 17 53.1 89 8 700 4503 MA 19 8 0.3 80 9 750 5500 EA 20 20 2.8 80 10 700 4700EA 29 7 1.3 65 5 800 4720 EA 29 7 0.3 65 6 800

In some embodiments, the one or more (meth)acrylates includes methylacrylate and glycidyl (meth)acrylate. In some embodiments, thepolyolefin co-polymer is Lotader® GMA AX 8900, as shown in Table 4.

TABLE 4 An exemplary Lotader ® GMA terpolymer Tensile Acrylic MeltGlycidyl Melting Strength Elongation Lotader ® Acrylic Ester IndexMethacrylate Point at Break at break Grades Ester (%) (g/10 mn) (%) (°C.) (MPa) (%) AX 8900 MA 24 6 8 65 4 1100

In Tables 2-4, “MA” refers to methyl acrylate, “EA” refers to ethylacrylate, and “BA” refers to butyl acrylate.

The polyester-based strapping compositions described herein can be made,in part, from a variety of polyesters. Non-limiting polyesters includearomatic polyesters, such as polyethylene terephthalate (PET),polypropylene terephthalate, polybutylene terephthalate, polyethylenenaphthalate, polybutylene naphthalate, polytetramethylene terephthalate,polycyclohexanedimethylene terephthalate, polyethylene isophthalate, andthe like.

The polyester used in the polyester-based strapping compositionsdescribed herein may be prepared from a dicarboxylic acid component anda diol component. Representative dicarboxylic acids include terephthalicacid, isophthalic acid, 2,6-naphthalenedicarboxylic acid,4,4′-diphenyldicarboxylic acid, adipic acid, and sebacic acid.Representative diols include ethylene glycol, 1,4-butanediol,1,4-cyclohexane dimethanol, and 1,6-hexanediol. The polyester includeshomo- or co-polyesters.

The polyester may be prepared by copolymerizing a polyester constituentand another acid component and/or a glycol component (e.g., an acidcomponent such as terephthalic acid, isophthalic acid, adipic acid,sebacic acid, glutaric acid, diphenylmethane dicarboxylic acid, dimeracid, or the like, and a glycol component such as ethylene glycol,diethylene glycol, hexamethylene glycol, bisphenol A, neopentyl glycolalkylene oxide adduct, or the like); degradable aliphatic polyesters,such as the polyhydroxyalkanoates (e.g., polyhydroxybutyrate,polyhydroxyvalerate, or polyhydroxybutyrate-co-hydroxyvalerate (PHBV)),polycaprolactone (PCL), polybutylene succinate, polyethylene succinate,polylactic acid (PLA), polymalic acid, polyglycolic acid,polylactide-co-glycolide, polydioxanone, poly(2-oxetanone),polyesteramide (PEA) and the like. Further polyesters include aromaticpolyester/polyether block copolymers, aromatic polyester/polylactoneblock copolymers, polyarylate, and the like. In certain embodiments, thepolyester of the strapping composition is a blend of any two or moresuch polyesters, or a co-polymer of any two or more such polyesters. Inother embodiments, the polyester includes polyethylene terephthalate,polybutylene terephthalate, polyethylene naphthalate, polyethyleneisophthalate, or combinations thereof. In certain embodiments, thepolyester includes polyethylene terephthalate and its copolymers. Insome embodiments, the polyester includes a recycled or a reprocessedpolyester.

The polyester may be a reprocessed or a recycled polyester. As usedherein, the term reprocessed polyester means a polyester polymerreclaimed from a production facility originally scrapped for not meetingquality control or specification targets. Amongst these can be includedpolyester products out of specification from compounding, extrusion, ormolding start-up and shut down production and/or polyester products fromgeneral production out of specification or otherwise not meeting productquality specifications. Also, included in the definition of reprocessedpolyester are polyester products processed to final use form but notmeeting product specifications, such as polyester product out of caliberor dimensions, color, shape, or polyester waste process material. Asused herein, the term recycled polyester means a polyester-based plasticreclaimed a posteriori from its final use from diverse sources,including, but not limited to, scrap from water bottles, detergentbottles, and other consumer products. Thus, the strapping compositionsand processes of preparing the strapping compositions may be consideredto be environmentally friendly, in that they minimize waste by notrequiring the use of virgin polyesters.

The strapping composition may include about 85.5 wt % to about 99.85 wt% of a polyester. In certain embodiments, the strapping compositionincludes about 85.5 wt % to about 90.0 wt % of a polyester. In certainembodiments, the strapping composition includes about 90.0 wt % to about95.0 wt % of a polyester. In certain embodiments, the strappingcomposition includes about 95.0 wt % to about 96.0 wt % of a polyester.In certain embodiments, the strapping includes about 96.0 wt % to about97.0 wt % of a polyester. In certain embodiments, the strappingcomposition includes about 97.0 wt % to about 98.0 wt % of a polyester.In certain embodiments, the strapping composition includes about 98.0 wt% to about 99.0 wt % of a polyester. In certain embodiments, thestrapping composition includes about 99.0 wt % to about 99.85 wt % of apolyester.

The strapping compositions described herein may further includepolyamide or polycarbonate additives. For example, in an additionalaspect, a strapping composition is provided that includes about 85.5 wt% to about 99.85 wt % of a polyester; and about 0.15 wt % to about 4.5wt % of a polyolefin co-polymer; where the polyolefin co-polymer ispolymerized from monomers including about 10 wt % to about 90 wt % ofpropylene or one or more (meth)acrylates; and about 10 wt % to about 90wt % of an olefin other than propylene or a (meth)acrylate; where thearticle optionally includes about 0.01 wt % to about 10 wt % of apolyamide or a polycarbonate. In some embodiments, the strappingcomposition includes a polyamide, where the polyamide includes nylon.

In one embodiment, the strapping compositions include a polyamide, wherethe polyamide is produced by condensation of a dicarboxylic acid with adiamine, by polymerizing a cyclic lactam, or by co-polymerizing a cycliclactam with a dicarboxylic acid/diamine salt. The polyamides includepolyamide elastomer resins. Suitable polyamide elastomer resins includea nylon, such as nylon 6, nylon 6-6, nylon 6-10, nylon 11, nylon 12, andco-polymers and blends of any two or more such polyamides.

Where the strapping composition includes a polyamide and/orpolycarbonate, it may include about 0.1 wt % to about 0.5 wt % of apolycarbonate and/or polyamide. In certain embodiments, the strappingcomposition includes about 0.5 wt % to about 1.0 wt % of a polyamideand/or polycarbonate. In certain embodiments, the strapping compositionincludes about 1.0 wt % to about 3.0 wt % of a polyamide and/orpolycarbonate. In certain embodiments, the strapping compositionincludes about 3.0 wt % to about 5.0 wt % of a polyamide and/orpolycarbonate. In certain embodiments, the strapping compositionincludes about 5.0 wt % to about 7.0 wt % of a polyamide and/orpolycarbonate. In certain embodiments, the strapping compositionincludes about 7.0 wt % to about 10.0 wt % of a polyamide and/orpolycarbonate. In certain of the above embodiments, the strappingcomposition includes polyamide. In certain of the above embodiments, thestrapping composition includes polycarbonate. In certain embodiments,the polyester includes polyethylene terephthalate and the polyamideincludes nylon.

The strapping compositions may also include polyolefin co-polymers,where the polyolefin co-polymers are polymerized from olefin monomersother than propylene or a (meth)acrylate, such as, for example,ethylene, 1-butene, 1-hexene, 1-octene, 1-decene, or styrene. In certainembodiments, the polyolefin co-polymers are polymerized from olefinmonomers other than propylene or a (meth)acrylate, such as ethylene. Incertain embodiments, the ethylene is polymerized to form linear lowdensity polyethylene. In certain embodiments, the ethylene ispolymerized to form branched low density polyethylene. As used herein,“low density polyethylene” has a specific gravity of about 0.861 toabout 0.94. In certain embodiments, the polyolefin co-polymer ispolymerized from propylene, ethylene, styrene, butadiene, or mixtures orcopolymers thereof, such as propylene-ethylene,styrene-ethylene-propylene, or styrene-ethylene-butene-styrene.

In another aspect, the olefin other than propylene or a (meth)acrylate,such as ethylene, is present about 10 wt % to about 30 wt %. In someembodiments, the olefin other than propylene or a (meth)acrylate, suchas ethylene, is present about 30 wt % to about 60 wt %. In someembodiments, the olefin other than propylene or a (meth)acrylate, suchas ethylene, is present from 61 wt % to 74 wt %.

It has been found that, in addition to the identity of the polyolefinco-polymer, the wt % of polyolefm co-polymer can impact certaincommercially relevant properties of the strapping composition includingtension retention, seal strength, resistance to splitting, and color oropacity. In certain embodiments, the strapping composition includesabout 0.15 wt % to about 0.5 wt % of the polyolefin co-polymer. Incertain embodiments, the strapping composition includes about 0.5 wt %to about 1.0 wt % of the polyolefin co-polymer. In another aspect, thestrapping composition includes about 1.0 wt % to about 1.2 wt % of thepolyolefin co-polymer. In some embodiments, the strapping compositionincludes about 1.2 wt % to about 1.4 wt % of the polyolefin co-polymer.In certain embodiments, the strapping composition includes about 1.4 wt% to about 1.6 wt % of the polyolefin co-polymer. In other embodiments,the strapping composition includes about 1.6 wt % to about 1.8 wt % ofthe polyolefin co-polymer. In certain embodiments, the strappingcomposition includes about 1.8 wt % to about 2.0 wt % of the polyolefinco-polymer. In certain embodiments, the strapping composition includesabout 2.0 wt % to about 2.5 wt % of the polyolefin co-polymer. Incertain embodiments, the strapping composition includes about 2.5 wt %to about 3.0 wt % of the polyolefin co-polymer. In certain embodiments,the strapping composition includes about 3.0 wt % to about 3.5 wt % ofthe polyolefin co-polymer. In certain embodiments, the strappingcomposition includes about 3.5 wt % to about 4.0 wt % of the polyolefinco-polymer. In certain embodiments, the strapping composition includesabout 4.0 wt % to about 4.5 wt % of the polyolefin co-polymer.

Melt flow index (MFI) is a measure of the ease of flow of the melt of athermoplastic polymer. It is defined as the mass of polymer, in grams,flowing in ten minutes through a capillary of a specific diameter andlength by a pressure applied via prescribed alternative gravimetricweights for alternative prescribed temperatures. The method is describedby American Society for Testing (ASTM) D1238 and ISO 1133. Melt flowrate is an indirect measure of molecular weight, with high melt flowrate corresponding to low molecular weight. At the same time, melt flowrate is a measure of the ability of the material's melt to flow underpressure. Melt flow rate is inversely proportional to viscosity of themelt at the conditions of the test, though it should be borne in mindthat the viscosity for any such material depends on the applied force.

In some embodiments, the polyolefin co-polymer has a melt temperature ofabout 60° C. to about 85° C. In some embodiments, the polyolefinco-polymer has a melt temperature of about 65° C. to about 80° C.

In certain embodiments, the polyolefin co-polymer has a MFI of betweenabout 0.1 g/10 min and about 5.0 g/10 min, as determined through astandard die (2.095×8 mm, at 230° C., under 2.16 kg of load) inaccordance with the methods described under ASTM D1238. In otherembodiments, the polyolefin co-polymer has a MFI of between about 0.1g/10 min and about 2.0 g/10 min. In certain embodiments, the polyolefinco-polymer has a MFI of between about 0.1 g/10 min and about 1.0 g/10min. In certain embodiments, the polyolefin co-polymer has a MFI ofbetween about 0.4 g/10 min and 0.6 g/10 min. In certain embodiments, thepolyolefin co-polymer has a MFI of about 0.5 g/10 min. In certainembodiments, the polyolefin co-polymer has a MFI of 0.49 g/10 min.

In certain embodiments, the strapping compositions are prepared from apolymer blend of polyester and polyolefin co-polymers, where thepolyester, such as PET, has an intrinsic viscosity below 0.86 dl/g,prior to processing. In certain embodiments, the polyester, such as PET,has an intrinsic viscosity at or below 0.82 dl/g. In some embodiments,the polyester, such as PET, has an intrinsic viscosity of between about0.70 dl/g and about 0.90 dl/g. In some embodiments, the polyester has anintrinsic viscosity of about 0.70 dl/g to about 0.84 dl/g. In someembodiments, the polyester, such as PET, has an intrinsic viscosity ofbetween about 0.75 dl/g and about 0.85 dl/g. In some embodiments, thepolyester, such as PET, has an intrinsic viscosity of between about 0.78dl/g and about 0.82 dl/g. In some embodiments, the polyester has anintrinsic viscosity of about 0.79 dl/g to about 0.82 dl/g. In yet otherembodiments, the polyester, such as PET, has an intrinsic viscosity ofabout 0.76 dl/g to about 0.80 dl/g, or about 0.74 dl/g to about 0.78dl/g. The above viscosity values refer to the viscosity of the polyesterprior to the extrusion step that processes the polyester-basedcomposition into strapping. In certain embodiments, the intrinsicviscosity of the above-described polymer blends can drop by about 0.1dl/g or 0.2 dl/g after processing at elevated temperatures, such asthrough typical extrusion operations.

In some embodiments, the article has an intrinsic viscosity of about0.60 dl/g to about 0.80 dl/g. In some embodiments, the article has anintrinsic viscosity of about 0.65 dl/g to about 0.72 dl/g.

Heavy-duty polyester strapping is especially prone to splitting. Incertain embodiments, polymer blends of polyester and polyolefinco-polymers, where the polyester has an intrinsic viscosity below 0.86dl/g, have been incorporated into heavy-duty strapping having a width ofat least about ⅝ inches (15 mm) and, optionally, a thickness of at leastabout 0.019 inches (0.48 mm) or, alternatively, exhibiting a breakstrength of at least about 1,300 lbs (591 kgs) of load. Heavy-dutystrapping can be prepared from a blend of polyester and polyolefinco-polymers, where the polyester has an intrinsic viscosity below 0.86dl/g. The resulting heavy-duty strapping exhibits resistance tosplitting, increased tension retention, increased seal strength, and/orand maintenance of polyester's traditional color and translucence. Incertain embodiments, heavy-duty strapping is prepared from polymerblends of polyester and polyolefin co-polymers, where the polyester hasan intrinsic viscosity from between about 0.70 dl/g to about 0.85 dl/g,or, for example, 0.70 dl/g, 0.71 dl/g, 0.72 dl/g, 0.73 dl/g, 0.74 dl/g,0.75 dl/g, 0.76 dl/g, 0.77 dl/g, 0.78 dl/g, 0.79 dl/g, 0.80 dl/g, 0.81dl/g, 0.82 dl/g, 0.83 dl/g, 0.84 dl/g, and 0.85 dl/g. It is thuscontemplated that heavy-duty strapping can be prepared from thecompositions described herein to have a reduced incidence of splitting.Reduced splitting can allow the strapping to be produced relatively thinand wide, for example, at least about 1 inch wide, or, in certainembodiments, at least about 1¼ inches wide, which in turn can reduce theneed to use protective bumpers in heavy-duty applications.

In certain embodiments, polymer blends of polyester and polyolefinco-polymers, where the polyester has an intrinsic viscosity below 0.86dl/g, have been incorporated into light-duty strapping (i.e., strappinghaving a width of less than ⅝ inches (15 mm) or, alternatively,exhibiting a break strength of less than about 1,300 lbs (591 kgs) ofload. Light-duty polyester strapping, while less-prone to splitting thanheavy-duty strapping, can also be improved by the addition of polyolefinco-polymers.

The resulting light-duty strapping exhibits resistance to splitting,increased tension retention, increased seal strength, and/or andmaintenance of polyester's traditional color and translucence. Incertain embodiments, light-duty strapping is prepared from polymerblends of polyester and polyolefin co-polymers, where the polyester hasan intrinsic viscosity from between about 0.50 dl/g to about 0.70 dl/g,or from between about 0.70 dl/g to about 0.85 dl/g, or, for example,0.50 dl/g, 0.55 dl/g, 0.60 dl/g, 0.65 dl/g, 0.70 dl/g, 0.71 dl/g, 0.72dl/g, 0.73 dl/g, 0.74 dl/g, 0.75 dl/g, 0.76 dl/g, 0.77 dl/g, 0.78 dl/g,0.79 dl/g, 0.80 dl/g, 0.81 dl/g, 0.82 dl/g, 0.83 dl/g, 0.84 dl/g, and0.85 dl/g. In some embodiments, the article has an intrinsic viscosityabout 0.60 dl/g to about 0.80 dl/g. In other embodiments, the articlehas an intrinsic viscosity about 0.65 dl/g to about 0.72 dl/g.

In certain embodiments, the above-described polymer blends of polyesterand polyolefin co-polymers where the polyester has an intrinsicviscosity below 0.86 dl/g have been incorporated into either light-dutyor heavy-duty strapping, where the polyester has been recycled orreprocessed.

In certain embodiments, the strapping is prepared from polyester andpolyolefin, each of which independently has a moisture content of lessthan about 0.5%. In certain embodiments, each of the polyester andpolyolefin independently has a moisture content of about 0.5% to about0.1%. In certain embodiments, each of the polyester and polyolefinindependently has a moisture content of about 0.1% to about 0.01%. Incertain embodiments, each of the polyester and polyolefin independentlyhas a moisture content of about 0.01% to about 0.001%.

The strapping may include additives, such as dyes and/or slip agents,that are believed to have minimal or no impact on the resistance tosplitting, tension retention, or seal strength of the strapping.

In some embodiments, the strapping has a tensile strength of about50,000 psi (3.45×10⁸ Pa) to about 60,000 psi (4.14×10⁸ Pa). In someembodiments, the strapping has a tensile strength of about 60,000 psi(4.14×10⁸ Pa) to about 70,000 psi (4.83×10⁸ Pa). In some embodiments,the strapping has a tensile strength of about 70,000 psi (4.83×10⁸ Pa)to about 80,000 psi (5.52×10⁸ Pa). Tensile strengths are measuredaccording to methods well known in the art such as those of ASTM D638.

Polyester-based strapping is commonly produced by forming continuousstrips of polyester-based material using a extrusion die and molecularlyorienting the strips in the longitudinal direction with stretching underheat and tension. Due to the molecular orientation, the strength of thestrapping increases in the longitudinal direction but reduces at thelateral/transverse direction due to the necking and bending stress atthe lateral direction. Thus, strapping that has been stretched in thelongitudinal direction only has a greater tendency to split in thelongitudinal direction when pulled tight, compared to unstretchedstrapping, or strapping stretched in two dimensions (i.e., bothlongitudinally and laterally).

Accordingly, in another aspect, the strapping compositions exhibitreduced brittleness, relative to existing compositions, rendering thestrapping composition less apt to split at the lateral/transversedirection. In yet another aspect, the strapping compositions exhibitcomparable brittleness, relative to existing compositions. In anotheraspect, the strapping compositions exhibit less opacity to visible lightrelative to existing compositions.

As indicated above, the strapping compositions are wrapped aroundobjects (e.g., boxes or pallets, loaded with lumber or bricks) until theends can be joined, drawn tight, and sealed. The resulting seal strengthof the strapping compositions must withstand the heavy load of thewrapped objects without breaking. Seal strength, as expressed herein, isdetermined by the load, in lbs, at which a ⅝″×0.035″ strapping seal willbreak as a percentage of 1,300 lbs (591 kgs) of load. For example, theseal of a ⅝″×0.035″ strapping that fails under 1069 lbs (486 kgs) ofload has a seal strength of 82% (1069/1300×100). One of ordinary skillin the art can calculate seal strengths for different sized straps,under different loads, other than a ⅝″×0.035″ strap. In certainembodiments, the seal strength of the strapping composition is about 80%to about 85%. In certain embodiments, the seal strength of the strappingcomposition is about 85% to about 90%. In certain embodiments, the sealstrength of the strapping compositions is about 88% to about 92%. Incertain embodiments, the seal strength of the strapping compositions isabout 88% to about 99%. In certain embodiments, the seal strength of thestrapping compositions is about 90% to about 95%. In certainembodiments, the seal strength of the strapping compositions is about95% to about 99%.

The strapping compositions can be sealed according to methods well-knownin the art. For example, such methods are described in U.S. Pat. Nos.7,625,628, 6,210,769, and 5,525,391, the entirety of each of which isincorporated herein by reference. For example, hot-seal welding orfriction welding can be used to weld the outer surfaces of the strappingtogether. Hot-seal welding employs a seal heater blade at elevatedtemperature to weld the outer surfaces of the strapping. Frictionwelding uses a rapid oscillating mechanism to generate heat and therebyweld the outer surfaces of the strapping. For example, in one aspect,the two ends of a strapping are wrapped around an object to be packaged,overlapped and pulled tight. The outer surface of overlapping layers areeither hot-seal welded or friction welded together, and the excessstrapping is cut. Seal strength of the welded ends is generallyproportional to the wt % of polyolefin co-polymers that is blended withpolyester prior to extrusion of the strapping composition. In certainembodiments, the strapping compositions, having lower viscosities, canattain greater wt % of polyolefin co-polymers without hindering theextrusion process. Thus, these strapping compositions having greater wt% of polyolefin co-polymers can likewise exhibit sufficient sealstrengths.

In certain embodiments, the strapping composition includes polyesterwith an intrinsic viscosity of between about 0.70 dl/g and about 0.84dl/g, and a seal strength of between about 80% and about 95%. In certainembodiments, the strapping composition includes polyester with anintrinsic viscosity of between about 0.75 dl/g and about 0.82 dl/g, anda seal strength of between about 80% and about 95%.

In some embodiments, the article has an intrinsic viscosity of about0.60 dl/g to about 0.80 dl/g. In some embodiments, the article has anintrinsic viscosity of about 0.65 dl/g to about 0.72 dl/g.

In certain embodiments, any of the above-described strappingcompositions has about 1.0 wt % to about 1.5 wt % polyolefinco-polymers. In certain embodiments, any of the strapping compositionshas about 1.5 wt % to about 2.0 wt % polyolefin co-polymers and a sealstrength of at least about 80%. In certain embodiments, any of theabove-described strapping compositions has about 2.0 wt % to about 2.5wt % polyolefin co-polymers. In certain embodiments, any of theabove-described strapping compositions has about 2.5 wt % to about 3.0wt % polyolefin co-polymers. In certain embodiments, any of theabove-described strapping compositions has about 3.0 wt % to about 3.5wt % polyolefin co-polymers. In certain embodiments, any of theabove-described strapping compositions has about 3.5 wt % to about 4.0wt % polyolefin co-polymers. In certain embodiments, any of theabove-described strapping compositions has about 4.0 wt % to about 4.5wt % polyolefin co-polymers.

Hot seal welding of the seals of the strapping compositions can beconducted at lower temperatures and over shorter welding times, relativeto conditions necessary to weld the seals of existing strappingcompositions. In certain embodiments, the ends of the strappingcompositions can be hot seal welded at seal heater blade temperatures ofabout 600° F. (316° C.) to about 975° F. (524° C.). In otherembodiments, the ends of the strapping compositions can be hot sealwelded at seal heater blade temperatures of about 750° F. (399° C.) toabout 900° F. (482° C.). In certain embodiments, the time required tohot seal weld the ends of the strapping compositions is between about0.05 seconds and about 1 second. In certain embodiments, the timerequired to hot seal weld the ends of the strapping compositions isbetween about 0.25 seconds and about 0.55 seconds. Consequently, thestrapping compositions can be manufactured in less time and at lowercost.

Stress relaxation is the extent to which a strapping composition losesan initial tension over a period of time. For example, a strappingcomposition having an applied stress of 75,000 psi for 1,000 hours mayexhibit essentially no stress relaxation, by retaining 100% of itsinitial tension, or it may exhibit some degree of stress relaxation, byretaining less than 100% of its initial tension. In another aspect, thestrapping composition exhibits a minimal and acceptable degree of stressrelaxation, where the strapping includes about 0.15 wt % to about 4.5 wt% of a polyolefin co-polymer, where the polyolefin co-polymer includesabout 26 wt % to about 90 wt % polypropylene, and about 10 wt % to about74 wt % of a polyolefin other than polypropylene, where the polyolefinco-polymer optionally further includes a diene. In certain embodiments,a strapping composition may concede a minimal degree of stressrelaxation in order to impart sufficient tension retention.

Some loads require strapping to have good initial tension as well asretained tension which keeps the strapping tight around the load even ifthe package settles and shrinks in size. The strapping compositions havesufficient tension retention. In some embodiments, the strappingcompositions have tension retention of about 70% to about 99%. In someembodiments, the strapping compositions have tension retention of about70% to about 75%. In some embodiments, the strapping compositions havetension retention of about 75% to about 80%. In some embodiments, thestrapping compositions have tension retention of about 80% to about 95%.In some embodiments, the strapping compositions have tension retentionof about 95% to about 99%. It is believed that the high wt % ofpolyolefin co-polymers may contribute to high degree of tensionretention of the strapping compositions.

In another aspect, the strapping has a continuous rectangular crosssection, where the strapping has a width of about 0.30 inches (0.80 cm)to about 2.75 inches (7.00 cm) and a thickness of about 0.015 inches(0.05 cm) to about 0.10 inches (0.3 cm). In some embodiments thestrapping has a width of about ⅜ inches (10 mm) to about 7/16 inches (11mm). In some embodiments the strapping has a width about 11 mm to about12 mm. In some embodiments the strapping has a width about ½ inches (12mm) to about 9/16 inches (14 mm). In some embodiments the strapping hasa width of about 9/16 inches (14 mm) to about ⅝ inches (16 mm). In someembodiments the strapping has a width of about ⅝ inches (16 mm) to about¾ inches (19 mm). In some embodiments the strapping has a width of about¾ inches (19 mm) to about 1¼ inches (32 mm). In some embodiments thestrapping has a width of about 1¼ inches (32 mm) to about 2½ inches (64mm). In some embodiments the strapping has a width of about 1 inch toabout 1¾ inches.

In certain embodiments, the strapping has a thickness of about 0.018inches (0.46 mm) to about 0.050 inches (1.27 mm). In some embodiments,the strapping has a thickness of about 0.018 inches (0.46 mm) to about0.020 inches (0.51 mm). In some embodiments the strapping has athickness of about 0.020 inches (0.51 mm) to about 0.024 inches (0.61mm). In some embodiments the strapping has a thickness of about 0.024inches (0.61 mm) to about 0.030 inches (0.76 mm). In some embodimentsthe strapping has a thickness of about 0.030 inches (0.76 mm) to about0.035 inches (0.89 mm). In other embodiments, the strapping has athickness of about 0.035 inches (0.89 nun) to about 0.040 inches (1.02mm). In other embodiments, the strapping has a thickness of about 0.040inches (1.02 mm) to about 0.050 inches (1.27 mm).

As described above, a further advantage of the strapping is that, incertain embodiments, it is less likely to damage goods, such as lumber,which the strapping is designed to combine or fasten. Commonly, existingstrapping must be fitted with “bumpers” that prevent the edges, or splitedges, of the tightly wrapped strapping from digging into fastened goodssuch as lumber. The strapping, particularly the heavy-duty strappinghaving a width of at least ⅝ inches (15 mm) or, alternatively,exhibiting a break strength of at least about 1,300 lbs (591 kgs) ofload, combines or fastens items with minimal splitting and withoutdigging into them as much as existing strapping, thus reducing ordispensing with the need for bumpers.

The strapping compositions can be made according to methods well-knownin the art. For example, such methods and the equipment used to makestrapping are described in U.S. Pat. Nos. 7,625,628, 6,210,769, and5,525,391.

In another aspect, a method for manufacturing an article is provided,where the article is a strapping, including the steps of forming amixture, heating the mixture, and extruding the heated mixture to formthe strapping. The mixture includes about 85.5 wt % to about 99.85 wt %of a polyester and about 0.15 wt % to about 4.5 wt % of a polyolefinco-polymer, where the polyolefin co-polymer is polymerized from monomersincluding about 10 wt % to about 90 wt % of propylene or one or more(meth)acrylates, and about 10 wt % to about 90 wt % of an olefin otherthan propylene or a (meth)acrylate.

In some embodiments, the method for manufacturing polyester-basedstrapping compositions utilize polyolefin co-polymers that derive, inpart, from propylene. In one embodiment, the polyolefin co-polymer ispolymerized from monomers including about 26 wt % to about 90 wt %propylene and about 10 wt % to about 74 wt % of the olefin other thanpropylene or a (meth)acrylate. In some embodiments, the polyolefinco-polymer is polymerized from monomers consisting essentially of: about26 wt % to about 39 wt % propylene; and about 61 wt % to about 74 wt %of the olefin other than propylene or a (meth)acrylate.

In some embodiments, the method for manufacturing polyester-basedstrapping compositions utilize polyolefin co-polymers that furtherinclude a diene constituent. In some embodiments, the olefin other thanpropylene or a (meth)acrylate of the polyolefin co-polymer includes adiene. In certain embodiments, the diene constituent includesethylidenenorbornene (ENB).

In some embodiments, the method for manufacturing polyester-basedstrapping compositions utilize polyolefin co-polymers that arepolymerized from monomers consisting essentially of about 26 wt % toabout 39 wt % propylene, about 61 wt % to about 74 wt % of the olefinother than propylene or a (meth)acrylate, and about 0.1 wt % to about 10wt % of a diene. In some embodiments, the polyolefin co-polymer ispolymerized from monomers including about 27 wt % to about 31 wt %propylene, about 68 wt % to about 73 wt % of the olefin other thanpropylene or a (meth)acrylate, and about 0.1 wt % to about 5 wt % of thediene. In some embodiments, the polyolefin co-polymer is polymerizedfrom monomers including about 29 wt % propylene, about 70.5 wt % of theolefin other than propylene or a (meth)acrylate, and about 0.5 wt % ofthe diene.

In some embodiments, the method for manufacturing polyester-basedstrapping compositions utilize polyolefin co-polymers that derive, inpart, from one or more (meth)acrylates. In some embodiments, thepolyolefin co-polymer is polymerized from monomers including about 10 wt% to about 50 wt % of one or more (meth)acrylates and about 50 wt % toabout 90 wt % of the olefin other than propylene or a (meth)acrylate. Insome embodiments, the polyolefin co-polymer is polymerized from monomersconsisting essentially of: about 10 wt % to about 50 wt % of one or more(meth)acrylates and about 50 wt % to about 90 wt % of the olefin otherthan propylene or a (meth)acrylate.

In some embodiments, the method for manufacturing polyester-basedstrapping compositions utilize polyolefin co-polymers that arepolymerized from monomers including about 15 wt % to about 40 wt % ofone or more (meth)acrylates and about 60 wt % to about 85 wt % ethylene.In some embodiments, the polyolefin co-polymer is polymerized frommonomers including about 10 wt % to about 20 wt % of one or more(meth)acrylates and about 80 wt % to about 90 wt % ethylene. In someembodiments, the polyolefin co-polymer is polymerized from monomersincluding about 21 wt % to about 30 wt % of one or more (meth)acrylatesand about 70 wt % to about 79 wt % ethylene. In some embodiments, thepolyolefin co-polymer is polymerized from monomers including about 31 wt% to about 40 wt % of one or more (meth)acrylates and about 60 wt % toabout 69 wt % ethylene. In certain embodiments, the polyolefinco-polymer is polymerized from monomers including about 41 wt % to about50 wt % of one or more (meth)acrylates and about 50 wt % to about 59 wt% ethylene.

In some embodiments, the method for manufacturing polyester-basedstrapping compositions utilize polyolefin co-polymers that arepolymerized from (meth)acrylates, and the (meth)acrylates include butylacrylate, methyl acrylate, glycidyl (meth)acrylate, methyl(meth)acrylate, or a combination of any two or more thereof. In someembodiments, the (meth)acrylates include butyl acrylate. In someembodiments, the (meth)acrylates include methyl acrylate.

In yet another aspect, a method for manufacturing an article isprovided, where the article is a strapping, including the steps offorming a mixture, heating the mixture, and extruding the heated mixtureto form the strapping. The mixture includes about 85.5 wt % to about99.85 wt % of a polyester and about 0.15 wt % to about 4.5 wt % of apolyolefin co-polymer. The polyolefin co-polymer is polymerized frommonomers including about 10 wt % to about 90 wt % of propylene or one ormore (meth)acrylates, about 10 wt % to about 90 wt % of an olefin otherthan propylene or a (meth)acrylate, and where the article optionallyincludes about 0.01 wt % to about 10 wt % of a polyamide or apolycarbonate. In some embodiments, the article includes a polyamide,and where the polyamide includes nylon.

In yet another aspect, a method for manufacturing a polyester-basedstrapping is provided, where the polyester has an intrinsic viscosity ofabout 0.70 dl/g to about 0.84 dl/g. In certain embodiments, thepolyester has an intrinsic viscosity of about 0.78 dl/g to about 0.82dl/g. In some embodiments, the polyester and polyolefin co-polymer each,independently, has an intrinsic viscosity of about 0.70 dl/g to about0.82 dl/g. In some embodiments, the polyester and polyolefin co-polymerhave a combined intrinsic viscosity of about 0.70 dl/g to about 0.82dl/g.

In certain embodiments, the method for manufacturing a polyester-basedstrapping composition utilizes, in part, polyethylene terephthalate. Inother embodiments, the method further adds polyamide, such as nylon, tothe strapping composition. In other embodiments, the polyamide is absentfrom the strapping composition.

In certain embodiments, the method for manufacturing a polyester-basedstrapping composition utilizes, in part, about 1.25 wt % to about 3.0 wt% of the polyolefin co-polymer. In certain embodiments, the methodutilizes one or more olefins other than propylene such as ethylene.

Prior to being extruded the precursor the polyester, polyolefinco-polymer, and optional polyamide and/or polycarbonate are mixed in theextruder and melted at a temperature range of about 200° C. to about340° C. to render the molten mixture flowable. In certain embodiments,the polyester, polyolefin co-polymer, and optional polyamide and/orpolycarbonate are melted at a temperature range of about 280° C. toabout 310° C.

The molten mixture of polyester, polyolefin co-polymer, and optionalpolyamide and/or polycarbonate are then forced through a die whichyields straps or sheets of a substantially rectangular cross section ofextruded material. The extruded material may be a single strand,multiple strands, or a sheet intended to be subsequently cut intoindividual straps.

In certain embodiments, the extruder is a single screw extruder. Infurther embodiments, the extruder is a twin screw extruder. Anunexpected advantage of the strapping is that it can be convenientlyproduced using a single screw extruder, whereas some conventionalstrapping compositions must be produced using a twin screw extruder inorder to achieve sufficient mixing of the components.

Stretching in the longitudinal direction strengthens the strapping dueto alignment of the polyester molecules along the longitudinal directionof the strapping. As noted above, polyester-based strapping is commonlyproduced by forming continuous strips of polyester-based material usinga extrusion die and molecularly orienting the strips in the longitudinaldirection with stretching under heat and tension. Generally, thestrength of the strapping increases in the longitudinal direction. Incertain embodiments, the strapping is stretched in the longitudinaldirection of the strapping about 3 to about 7 times an initial,unstretched length of the strapping. The strapping compositions can bestretched according to methods well-known in the art. For example, suchmethods are described in U.S. Pat. Nos. 7,625,628, 6,210,769, and5,525,391.

Prior to stretching the precursor strapping is heated to a temperaturerange between the softening point and the melting point of thestrapping. In certain embodiments, the strapping compositions are morereadily stretched due, in part, to greater percentages of polyolefinco-polymers that are blended with polyester prior to extrusion of theprecursor strapping composition. In certain embodiments, the strappingcompositions are stretched at lower temperatures than temperaturesrequired to stretch conventional strapping compositions. In certainembodiments, the strapping compositions are stretched at temperatures ofabout 110° C. to about 130° C. In certain embodiments, the strappingcompositions are stretched at temperatures of about 130° C. to about150° C. In certain embodiments, the strapping compositions are stretchedat temperatures of about 150° C. to about 170° C. In certainembodiments, the strapping compositions are stretched at temperatures ofabout 170° C. to about 190° C. In certain embodiments, the strappingcompositions are stretched at temperatures of about 190° C. to about210° C.

One skilled in the art will readily realize that all ranges discussedcan and do necessarily also describe all subranges therein for allpurposes and that all such subranges also form part and parcel of thisdisclosure. Any listed range can be easily recognized as sufficientlydescribing and enabling the same range being broken down into at leastequal halves, thirds, quarters, fifths, tenths, etc. As a non-limitingexample, each range discussed herein can be readily broken down into alower third, middle third and upper third, etc.

All publications, patent applications, issued patents, and otherdocuments referred to in this specification are herein incorporated byreference as if each individual publication, patent application, issuedpatent, or other document was specifically and individually indicated tobe incorporated by reference in its entirety. Definitions that arecontained in text incorporated by reference are excluded to the extentthat they contradict definitions in this disclosure.

The present aspects and embodiments, thus generally described, will beunderstood more readily by reference to the following examples, whichare provided by way of illustration and are not intended to be limiting.

EXAMPLES

The following terms and abbreviations are used: “SS” is seal strength,which is calculated as seal strength (lbs)/1300 (lbs)×100. “TR” istension retention after 24 hours by placing the strapping under a loadand measuring tension at an initial time point and re-measuring 24-hourslater. The tension value at 24-hours is divided by the value at theinitial time point and multiplied by 100. “PET IV” is the intrinsicviscosity of the polyethylene terephthalate (PET) component of thepolymer mixture, before processing the mixture through the extruder tomake the strapping. “Strap IV” is the intrinsic viscosity of the polymerblend used to make the strapping. Additive “Y” is a polyolefinco-polymer polymerized about 91 wt % propylene and 9 wt % ethylene.Additive “Z” is a polyolefin co-polymer polymerized from 29 wt %propylene, 70.5 wt % ethylene, and 0.5 wt % ethylidenenorbornene (ENB).Additive “YY” is a copolymer made about 65% ethylene and about 35% butylacrylate. Additive “ZZ” is a copolymer made about 68% ethylene, about24% methyl acrylate and about 8% glycidyl methacrylate. The term “n.t.”means “not tested.” “Additive %” indicates wt %, “MFI” is melt flowindex, “Ave” is average, and “S.D.” is standard deviation. “CT” is“clear/transparent” and “MC” is “milky/cloudy.”

Example 1

Seal efficiencies, tension retention and split resistance test resultsfor strappings made from co-polymers derived from ethylene and propylenemonomers are depicted in Table 5. “VK-30 & MHT80 Split Testing” wereconducted to measure the resistance to splitting of strappingcompositions with the dimensions ⅝″×0.035″. This procedure utilized aVK-30 Titan sealing head, or a MHT80 Signode head to place the strappingunder simulated high tensions of 280 lbs to 340 lbs, similar to those oflumber or brick applications. Tension was applied to strapping at bothends of the seal, which was held approximately 1″ to 3″ from a metalplate. Tension was then released, allowing the strapping seal to slapagainst a metal plate which can cause longitudinal splitting along thestrapping nearest to the seal. The strapping was then removed from “rollguides” of the VK30 Titan sealing head and inspected for splitting.

Splitting results are depicted in FIG. 2. Specifically, strappingcompositions D1-D5 exhibited less than or equal to 50% splitting undersimulated high tensions of 280 lbs to 340 lbs Further, none of strappingcompositions D1-D5 exhibited splitting under 280 lbs of simulatedtension. Thus, compositions D1-D5 exhibited reduced splitting relativeto the polyester strapping composition A and polyester-siliconecomposition B.

The strapping of compositions D1-D5 exhibited translucence to visiblelight comparable to conventional PET strapping having no polyolefinco-polymer additive. The strapping of compositions D1-D5 also exhibitedgreater translucence to visible light compared to PET strapping C havinga polyolefin co-polymer additive polymerized about 91% propylene andabout 9% ethylene.

TABLE 5 Split Testing Results of Strappings Made From Co-PolymersDerived From Ethylene and Propylene Monomers. Strap Individual Strapping(⅝″ × .035″) Properties A B C D1 D2 D3 D4 D5 Composition PET IV 0.810.86 0.81 0.81 0.81 0.81 0.81 0.81 Additive None Silicone Y Z Z Z Z ZAdditive MFI — — — 0.49 0.49 0.49 0.49 0.49 Additive % 0 0.375 1.250.875 1.25 1.5 1.75 2 Splitting 280 lbs 3/5 2/7 0/6 0/6 0/6 0/6 0/6 0/6300 lbs 5/6 6/6 2/7 2/6 2/6 0/6 1/7 2/7 320 lbs 5/5 6/6 3/6 4/6 4/6 3/64/6 4/6 340 lbs 6/6 5/6 3/6 4/6 6/6 5/6 5/6 3/6 Split % 83 79 32 42 5033 40 36 Seal Seals made on 1069 1223 1188 1174 1202 1206 1165 1178Strength a VK-30 head (lbs) SS % 82 94 91 90 92 93 90 91 Seals made on a1139 1278 1201 1168 1172 1160 1173 1195 MHT80 Signode head (lbs) SS % 8898 92 90 90 89 90 92 Tension TR % 68 n.t. 73 n.t. 72 70 73 73 RetentionAdditive YY is a copolymer made about 65% ethylene and about 35% butylacrylate. Additive ZZ is a copolymer made about 68% ethylene, about 24%methyl acrylate and about 8% glycidyl methacrylate.

Example 2

The melt flow index “MFI” molten extrusion rate (in g/10 min) forAdditive Z was determined through a standard die (2.095×8 mm, at 230°C., under 2.16 kg of load) in accordance with the methods describedunder American Society for Testing (ASTM) D1238.

TABLE 6 Melt Flow Index values for Additive Z: MFI (g/10 min) Ave. S.D.0.49 0.49 0.01 0.50 0.49

TABLE 7 Split Testing Results of Strappings Made From Co-PolymersDerived From Ethylene and Acrylate Monomers. Individual Strapping (⅝″ ×.035″) Strap Properties E F G1 G2 H I1 I2 Composition PET IV 0.80 0.800.80 0.80 0.80 0.80 0.80 Strap IV 0.703 0.659 0.68 0.68 0.705 0.7060.694 Additive None Silicone YY YY Silicone ZZ ZZ Additive (%) 0 1.75 11.75 1.75 1 2 Width (in.) 0.613 0.603 0.604 0.609 0.615 0.608 0.615Gauge (in.) 0.347 0.350 0.349 0.350 0.350 0.350 0.350 Weight 6 5.42 5.425.49 5.55 5.49 5.5 (g/ft) L* 45.3 48 47.7 53.4 48.4 42.2 46.2 SplittingBreak (lbs.) 1449 1406 1429 1423 1406 1515 1461 Eb (%) 11.2 10.6 10.610.6 11.5 11.6 12.3 STD Split Test  0/10  0/10  0/10  0/10  0/10  0/10 0/10 280 lbs 3/5 0/5 0/5 1/9  3/13  3/10 0/8 300 lbs 4/6 1/6 2/5 0/51/6 5/5 4/8 320 lbs 4/6 3/6 2/6 1/5 3/6 4/6 5/6 340 lbs 5/5 4/6 3/6 1/66/6 4/6 5/6 Split % 73 35 32 12 42 59 41 Seal Seals made on 1101 12161259 1223 1120 1204 1253 Strength a VK-30 head (lbs.) SE (%) 85 94 97 9486 93 96 Seals made on a 1129 1197 1243 1209 1191 1230 1215 MHT80Signode head (lbs) SE (%) 87 92 96 93 92 95 93 Tension 24-Hr TR (%) 7271 74 76 72 70 73 Retention L* is a relative measure of coloration asmeasured by a spectrophotometer. Eb % is the extent of elongation thatoccurs prior to breakage. The STD split test attempts to split thestrapping by subjecting the strapping to longitudinal folding withpliers or a test instrument.

Example 3

Seal efficiencies, tension retention and split resistance test resultsfor strappings made from co-polymers derived from ethylene and acrylatemonomers are depicted in Table 7. Specifically, strapping compositionsthat include additive 1.75% YY (a copolymer made about 65% ethylene andabout 35% butyl acrylate) yielded improved split resistance over thecontrol product containing 1.75% silicone. The occurrence of splits,using the VK30 test with contact plate, was reduced by 66% for tests runat 280 lbs to 340 lbs applied tension. At the 1% level, additive YYimproved split resistance by about 9% over the control product.Strapping compositions that include additive YY exhibited fewersplitting frequencies relative to control strappings subjected tosimulated high tensions of 280 lbs to 340 lbs. Further, none ofstrapping compositions that include additive YY exhibited splitting at280 lbs of simulated tension. Thus, compositions that include additiveYY exhibited reduced splitting relative to the polyester strappingcomposition E and the polyester-silicone composition F.

Split resistance of compositions that include 1% of additive YY (32%)was better than the control products (35% and 42%) containing 1.75%silicone. MHT80 and VK30 seal efficiencies were similar to EPDM at thehigher addition rate. Seal efficiencies and tension retentions alsoimproved for compositions that include 1% of additive YY relative tocontrol products lacking an additive or containing 1.75% silicone.

While certain embodiments have been illustrated and described, it shouldbe understood that changes and modifications can be made therein inaccordance with ordinary skill in the art without departing from theinvention in its broader aspects as defined in the following claims.

1-62. (canceled)
 63. An article comprising a polyolefin co-polymerconsisting of about 26 wt % to about 90 wt % propylene and about 10 wt %to about 74 wt % of polyethylene, wherein the article is a strappingarticle.
 64. The article of claim 63, wherein the polyolefin co-polymerconsists of about 16 wt % to about 39 wt % propylene and about 61 wt %to about 74 wt % of the olefin other than propylene.
 65. The article ofclaim 63 further comprising a polyester.
 66. The article of claim 65,wherein the polyester has an intrinsic viscosity of 0.70 dl/g to 0.84dl/g.
 67. The article of claim 65, wherein the polyester is selectedfrom the group consisting of polyethylene terephthalate, polypropyleneterephthalate, polybutylene terephthalate, polytetramethyleneterephthalate, polycyclohexanedimethylene terephthalate, polyethylenenaphthalate, polybutylene naphthalate, polyethylene isophthalate, and acombination of any two or more thereof.
 68. The article of claim 63further comprising a polyamide.
 69. The article of claim 68, wherein thepolyamide is nylon.
 70. The article of claim 68 including about 0.01 wt% to about 10 wt % of the polyamide.
 71. The article of claim 63 furthercomprising a polycarbonate.
 72. The article of claim 71 including about0.01 wt % to about 10 wt % of the polycarbonate.
 73. The article ofclaim 63 which is free of free polyethylene (non-co-polymerized), freepolypropylene (non-co-polymerized), or physical mixtures thereof.